The threat of a tube strike during next year's Olympics appears to have abated after London Underground bosses claimed to have reached a deal with train drivers.

Under the terms of the deal, all tube drivers will receive a one-off payment of £500 and will be paid more during the Games if they work shifts that finish after 1.30am or last more than eight hours.

LU's managing director, Mike Brown, said the agreement was a "good deal" for drivers and thousands of Olympics spectators.

"LU is committed to ensuring that the train service we provide contributes to the successful operation of the Games and I am pleased that we and the unions have been able to engage in constructive dialogue to reach this agreement," he said. The deal covers the period from 27 July to 9 September.

The RMT said its executive committee had yet to approve the deal. Bob Crow, the RMT general secretary, said: "[Transport for London] are now looking seriously at the role our members will play in delivering the transport plans for the London Olympics and the detail of this offer will be considered by the RMT executive in consultation with our representatives."

Union sources said the RMT, which represents a significant number of drivers, still had "serious reservations" about the agreement.

LU said staff representatives on the Trains Functional Council, the body that negotiates pay deals for tube drivers, had approved the deal. Aslef, the main drivers' union, has accepted the agreement.

London Underground did not confirm whether the deal contained a no-strike agreement, under which unions would agree that all disputes arising during the Olympics would be referred to the Acas conciliation service. Network Rail, the owner of Britain's railway tracks, included such a clause in its Olympics pay deal, which also included a one-off payment.

London Underground said talks over a wider pay deal were continuing. An Olympics deal with tube drivers was considered vital by London Underground and the mayor's office because they have enough industrial muscle to bring one of the capital's main transport systems to a halt.